pedatric thyroid disorder?

my daughter is 10 and last year started with numerous syptoms she has been tested for everthing from migranes to epilepsy the on thing that has so far come back positive was thyroid peroxidase ab was 20 her other results were thyroxine 10.5 5.0-11.6 normal we just had her retested and the results werethyroxine 8.2 5.0-11.6 normal free thyroxine index 7.8 6-10.5 normal thyrotropin 1.1 0.3-3.0 normal ana ifa <40 please any info would be greatly appreciated.